Description:
------------
Hello,

When the setting `variables_order` is set to "", the documentation [0] says:

>  Setting to "" means no superglobals will be set.

But instead the default "EGPCS" is set.

The only way I found of disable superglobals (because `track_vars` is deprecated) is to set `variables_order` to a letter different of "EGPCS", like "N". This way superglobals are set (`isset($_SERVER)` still true), but not populated.

[0]: http://php.net/manual/en/ini.core.php#ini.variables-order

Test script:
---------------
% php -n -d variables_order="" -r "var_dump(\$_SERVER);"
% php -n -d variables_order="N" -r "var_dump(\$_SERVER);"

Expected result:
----------------
array(0) {
}
array(0) {
}

Actual result:
--------------
array(52) {
...
  ["SHELL"]=>
  string(8) "/bin/zsh"
  ["TERM"]=>
  string(14) "xterm-256color"
...
}
array(0) {
}